Impact-induced energy release characteristics of Ti-Zr-Hf-Ta high-entropy alloys by using a temperature-pressure synchronous measurement method

Abstract

Energetic structural materials (ESMs) are a new type of materials with structural strength and reactivity, and their impact-induced energy release characteristics are greatly influenced by the fragmentation behavior. In this study, the dynamic fragmentation behavior and energy release characteristics of Ti-Zr-Hf-Ta high-entropy alloys (HEAs) with different precipitate content were investigated based on split Hopkinson pressure bars (SHPB) tests. To quantitatively evaluate the reactivity of ESMs, a temperature-pressure synchronous measurement method combined with a modified calculation model for quasi-sealed chamber was proposed. The results showed that the precipitates were distributed at the grain boundaries. As the precipitate content increased, the quasi-static yield strengths increased from 1004 to 1132 MPa, the dynamic yield strengths increased from 1672 to 1874 MPa, while the fracture strains decreased from 0.47 to 0.29, and correspondingly, the released energy increased from 14±2–511±154 J/g. The results demonstrated that the impact-induced energy release characteristics of the materials are closely related to the fracture strain. It can be confirmed that the alloys with lower plasticity are more likely to fracture under impact conditions, and the combustion reaction will be more violent, which is well consistent with the measurement of the energy-release amounts. High-speed infrared temperature measurement and microstructural photography also provided the underlying mechanism: the fragment size of low plasticity materials is smaller and the local hot spots are more dispersed, both of which are conducive to the combustion reaction. By using this method, the relationship among mechanical properties, fragmentation behavior, and energy release characteristics can be established, and the results will provide new insights into the development of ESMs with superior energy release under impact loading and applicable mechanical properties for potential applications.